1. Field of the Invention
The present invention relates to a chip size semiconductor device that can be mounted densely on a packaging substrate with high mounting efficiency and high reliability, and a method for manufacturing the same. In particular, the present invention relates to a semiconductor device that can be manufactured at a semiconductor wafer level and has a highly reliable structure, and a method for manufacturing the same.
2. Description of Related Art
Accompanying the reduction in size and weight and the densification of portable appliances in recent years, there has been an increasingly denser mounting of semiconductor packages having a lead terminal as an external electrode. In order to mount such semiconductor packages on a packaging substrate more densely, a technology of mounting a chip size semiconductor package on a packaging substrate has been developed.
The following is a description of a conventional semiconductor device, with reference to accompanying drawings. FIG. 3A is a perspective view showing a conventional semiconductor device 90. FIG. 3B is a sectional view thereof taken along the line Axe2x80x94A shown in FIG. 3A.
The semiconductor device 90 includes a substantially rectangular parallelepiped semiconductor chip 93. On the periphery of a principal surface of the semiconductor chip 93, a plurality of electrode pads 92 are provided. Each of the electrode pads 92 is connected to a semiconductor integrated circuit element (not shown) formed inside the semiconductor chip 93. On the principal surface of the semiconductor chip 93, an insulating layer 81 is formed in such a manner as to be surrounded by the plurality of electrode pads 92. The insulating layer 81 is formed of a low-elasticity resin having an insulating property. On the insulating layer 81, a plurality of contact pads 83 are formed in a matrix form. Each of the contact pads 83 is connected to one of the plurality of electrode pads 92 via a fine wiring layer 98, which is formed of a metal conductor. An insulating resin layer 82 with a plurality of openings respectively reaching the contact pads 83 also is formed on the insulating layer 81. In the perspective view of FIG. 3A, a part of the insulating resin layer 82 is omitted for the purpose of illustrating the electrode pads 92, the insulating layer 81, the wiring layers 98 and the contact pads 83 that are formed under the insulating resin layer 82. In each of the openings provided in the insulating resin layer 82, a substantially spheroidal solder ball 97 is placed so as to be connected to the contact pad 83. Each of the solder balls 97 forms a protruding electrode.
As described above, the plurality of electrode pads 92 provided on the periphery of the principal surface of the semiconductor chip 93 are rewired via the fine wiring layers 98 and the contact pads 83 to the solder balls 97, which are arranged two-dimensionally on the principal surface of the semiconductor chip 93.
A method for manufacturing the conventional semiconductor device 90 with the above structure will be described with reference to FIGS. 4A to 4G. FIGS. 4A to 4G are sectional views for describing the method for manufacturing the conventional semiconductor device 90.
First, as shown in FIG. 4A, a semiconductor wafer 91 in which a plurality of the substantially rectangular parallelepiped semiconductor chips 93 are formed is prepared. The plurality of electrode pads 92 are arranged on the periphery of the principal surface of each of the semiconductor chips 93 formed in the semiconductor wafer 91. Each of the electrode pads 92 is connected to the semiconductor integrated circuit element (not shown) formed inside the semiconductor chip 93.
Next, as shown in FIG. 4B, on the principal surface of each of the semiconductor chips 93 formed in the semiconductor wafer 91, the insulating layer 81 is formed in such a manner as to be surrounded by the plurality of electrode pads 92. The insulating layer 81 is formed of a low-elasticity resin having an insulating property.
Then, as shown in FIG. 4C, on the insulating layer 81 formed on the principal surface of each of the semiconductor chips 93 formed in the semiconductor wafer 91, a plurality of the contact pads 83 are formed in a matrix form. The fine wiring layer 98 for connecting each of the contact pads 83 to one of the plurality of electrode pads 92 is formed with a metal conductor.
Thereafter, as shown in FIG. 4D, the insulating resin layer 82 with a plurality of the openings respectively reaching the contact pads 83 is formed on the insulating layer 81 formed on the principal surface of the semiconductor chip 93.
Subsequently, as shown in FIG. 4E, in each of the openings provided in the insulating resin layer 82, the substantially spheroidal solder ball 97 is placed so as to be connected to the contact pad 83. Each of the solder balls 97 forms the protruding electrode.
Then, as shown in FIG. 4F, the semiconductor wafer 91 and the insulating resin layer 82 are cut with a rotating blade 23 from above the semiconductor wafer 91 along a dicing scribe line 84 set between the plurality of semiconductor chips 93 formed in the semiconductor wafer 91, thus obtaining a semiconductor device as shown in FIG. 4G. The semiconductor device that has been separated from the semiconductor wafer 91 and is shown in FIG. 4G has the same structure as the semiconductor device 90 described above referring to FIGS. 3A and 3B. According to the above-described processes, a high-density chip-type semiconductor device suitable for being mounted on a substrate can be manufactured.
However, in the conventional semiconductor device 90 described above, since the fine wiring layers 98 for connecting the electrode pads 92 provided on the principal surface of the semiconductor chip 93 and the solder balls 97 serving as the protruding electrodes provided on the insulating layer 81 formed on the principal surface of the semiconductor chip 93 extend over a slope-like step between the insulating layer 81 and the principal surface of the semiconductor chip 93, the wiring layers 98 may break at this slope-like step. Accordingly, there is a problem of poor reliability of the structure for connecting the electrode pads provided on the periphery of the principal surface of the semiconductor chip and the protruding electrodes provided substantially at the center of the principal surface of the semiconductor chip.
It is an object of the present invention to solve the problem described above and to provide a semiconductor device having a highly reliable structure, and a method for manufacturing the same.
It is a further object of the present invention to provide a semiconductor device, in which a structure for connecting electrode pads and protruding electrodes provided on a principal surface of a semiconductor chip has an improved reliability, and a method for manufacturing the same.
A semiconductor device according to the present invention is a semiconductor device to be mounted on a packaging substrate. The semiconductor device includes a first semiconductor chip, a plurality of first electrode pads provided on a surface of the first semiconductor chip on a side of the packaging substrate, for electrically connecting the first semiconductor chip to the packaging substrate, a second semiconductor chip mounted on the first semiconductor chip so as to be surrounded by the plurality of first electrode pads, and protruding electrodes respectively provided so as to protrude from the first electrode pads toward the packaging substrate so that their surfaces are substantially flush with a surface of the second semiconductor chip on a side of the packaging substrate.
Accordingly, the protruding electrodes for electrically connecting the first semiconductor chip to the packaging substrate respectively are provided so as to protrude from the first electrode pads provided on the surface of the first semiconductor chip on the side of the packaging substrate toward the packaging substrate, and the surfaces of the protruding electrodes are substantially flush with the surface of the second semiconductor chip on the side of the packaging substrate. The second semiconductor chip is mounted on the surface of the first semiconductor chip on the side of the packaging substrate. This improves the reliability of the structure for electrically connecting the first semiconductor chip provided in the semiconductor device to the packaging substrate, compared with the conventional structure in which the wiring layers break easily at the slope-like step between the insulating layer and the principal surface of the first semiconductor chip, because no protruding electrode is provided.
It may be possible to further include a plurality of second electrode pads, provided on the surface of the first semiconductor chip, for electrically connecting the second semiconductor chip to the first semiconductor chip. The surface of the first semiconductor chip is provided with a resin formed so as to seal at least a gap between the first semiconductor chip and the second semiconductor chip.
A surface of the resin may be formed to be substantially flush with the surface of the second semiconductor chip on the side of the packaging substrate.
The plurality of first electrode pads may be provided on a periphery of the surface of the first semiconductor chip.
It may be possible further to include external electrodes respectively provided so as to correspond to the protruding electrodes, for connecting the protruding electrodes to the packaging substrate on which the semiconductor device is to be mounted.
The external electrodes may be arranged on the surface of the second semiconductor chip on the side of the packaging substrate. It may be possible further to include wirings for connecting the protruding electrodes to the external electrodes corresponding to the protruding electrodes.
First ends of the wirings may be connected to the surfaces of the protruding electrodes, and second ends of the wirings may extend on the surface of the second semiconductor chip on the side of the packaging substrate and be connected to the external electrodes.
It may be possible further to include a resist resin that is provided so as to cover the second semiconductor chip and the wirings and has a plurality of openings formed for connecting the second ends of the wirings to the external electrodes.
The external electrodes may be provided on the surfaces of the protruding electrodes corresponding to the external electrodes.
The external electrodes each may be formed of a ball electrode.
A method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device to be mounted on a packaging substrate. The method includes a semiconductor wafer preparation process for preparing a semiconductor wafer, the semiconductor wafer including a plurality of first semiconductor chips whose surfaces on a side of the packaging substrate are provided with a plurality of first electrode pads, for electrically connecting the semiconductor device to the packaging substrate, a protruding electrode forming process for forming protruding electrodes respectively so as to protrude from the first electrode pads, which are provided on the surfaces of the first semiconductor chips on the side of the packaging substrate, toward a direction perpendicular to the surfaces, a second semiconductor chip mounting process, after the protruding electrode forming process, for mounting second semiconductor chips on the first semiconductor chips respectively so as to be surrounded by the plurality of first electrode pads provided on the first semiconductor chips, and a grinding process for grinding surfaces of the protruding electrodes and surfaces of the second semiconductor chips on a side opposite to the first semiconductor chips so that the surfaces of the protruding electrodes and the surfaces of the second semiconductor chips on the side opposite to the first semiconductor chips are substantially flush with each other.
Accordingly, since the surfaces of the protruding electrodes and the surfaces of the second semiconductor chips on the side opposite to the first semiconductor chips are ground together, the surfaces of the protruding electrodes and the surfaces of the second semiconductor chips on the side opposite to the first semiconductor chips are made substantially flush with each other. This improves the reliability of the structure for electrically connecting the first semiconductor chip provided in the semiconductor device to the packaging substrate, compared with the conventional structure in which the wiring layers break easily at the slope-like step between the insulating layer and the principal surface of the first semiconductor chip, because no protruding electrode is provided.
A plurality of second electrode pads for electrically connecting the second semiconductor chips to the first semiconductor chips may be provided on the surfaces of the first semiconductor chips formed in the semiconductor wafer prepared in the semiconductor wafer preparation process. The method further may include a resin forming process, before the grinding process, for forming a resin on the surfaces of the first semiconductor chips for sealing at least a gap between the first semiconductor chips and the second semiconductor chips.
The resin forming process may form the resin so as to cover the protruding electrodes respectively formed on the first electrode pads of the first semiconductor chips.
The protruding electrode forming process may form the protruding electrodes into a cylindrical or prismatic shape.
The plurality of first electrode pads provided on each of the first semiconductor chips formed in the semiconductor wafer prepared in the semiconductor wafer preparation process may be arranged on a periphery of the surface of each of the first semiconductor chips.
The second semiconductor chip mounting process may flip-chip mount the second semiconductor chips on the first semiconductor chips.
The method further may include a wiring forming process, after the grinding process, for forming wirings connected to the protruding electrodes. The wiring forming process may form the wirings so that first ends of the wirings are connected to the surfaces of the protruding electrodes, and second ends of the wirings extend on the surfaces of the second semiconductor chips on the side opposite to the first semiconductor chips.
The method further may include an external electrode forming process, after the wiring forming process, for forming a plurality of external electrodes for connecting the wirings to the packaging substrate on which the semiconductor device is to be mounted. The external electrodes each may be formed of a ball electrode.
The method further may include a resist resin forming process, after the wiring forming process, for forming a resist resin having a plurality of openings reaching the second ends of the wirings.
The method further may include a process, after the resist resin forming process, for forming external electrodes respectively in the openings of the resist resin in order to connect the wirings to the packaging substrate on which the semiconductor device is to be mounted.
The method further may include a process, after the grinding process, for dividing the semiconductor wafer in each of the first semiconductor chips.
With respect to the first semiconductor chips, surfaces of the protruding electrodes formed in the protruding electrode forming process may be lower than surfaces of the second semiconductor chips on the side of the packaging substrate. The second semiconductor chips are mounted in the second semiconductor chip mounting process.